{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,30]],"date-time":"2026-09-30T11:43:56Z","timestamp":1790768636010,"version":"4.1.0"},"reference-count":44,"publisher":"MDPI AG","issue":"8","license":[{"start":{"date-parts":[[2024,4,10]],"date-time":"2024-04-10T00:00:00Z","timestamp":1712707200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Science Foundation of China","award":["52073083"],"award-info":[{"award-number":["52073083"]}]},{"name":"National Natural Science Foundation of China","award":["51603065"],"award-info":[{"award-number":["51603065"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>Shape-shifting polymers usually require not only reversible stimuli-responsive ability, but also strong mechanical properties. A novel shape-shifting photochromic hydrogel system was designed and fabricated by embedding hydrophobic spiropyran (SP) into double polymeric network (DN) through micellar copolymerisation. Here, sodium alginate (Alg) and poly acrylate-co-methyl acrylate-co-spiropyran (P(SA-co-MA-co-SPMA)) were employed as the first network and the second network, respectively, to realise high mechanical strength. After being soaked in the CaCl2 solution, the carboxyl groups in the system underwent metal complexation with Ca2+ to enhance the hydrogel. Moreover, after the hydrogel was exposed to UV-light, the closed isomer of spiropyran in the hydrogel network could be converted into an open zwitterionic isomer merocyanine (MC), which was considered to interact with Ca2+ ions. Interestingly, Ca2+ and UV-light responsive programmable shape of the copolymer hydrogel could recover to its original form via immersion in pure water. Given its excellent metal ion and UV light stimuli-responsive and mechanical properties, the hydrogel has potential applications in the field of soft actuators.<\/jats:p>","DOI":"10.3390\/polym16081031","type":"journal-article","created":{"date-parts":[[2024,4,10]],"date-time":"2024-04-10T03:07:48Z","timestamp":1712718468000},"page":"1031","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Ion-Cross-Linked Hybrid Photochromic Hydrogels with Enhanced Mechanical Properties and Shape Memory Behaviour"],"prefix":"10.3390","volume":"16","author":[{"given":"Shijun","family":"Long","sequence":"first","affiliation":[{"name":"Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Longzhong Laboratory, Xiangyang 441000, China"},{"name":"New Materials and Green Manufacturing Talent Introduction and Innovation Demonstration Base, Hubei University of Technology, Wuhan 430068, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Fan","family":"Chen","sequence":"additional","affiliation":[{"name":"Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Han","family":"Ren","sequence":"additional","affiliation":[{"name":"Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yali","family":"Hu","sequence":"additional","affiliation":[{"name":"Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Chao","family":"Chen","sequence":"additional","affiliation":[{"name":"Hubei Key Laboratory of Polymer Materials, Hubei University, Wuhan 430062, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3697-7409","authenticated-orcid":false,"given":"Yiwan","family":"Huang","sequence":"additional","affiliation":[{"name":"Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Longzhong Laboratory, Xiangyang 441000, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xuefeng","family":"Li","sequence":"additional","affiliation":[{"name":"Hubei Provincial Key Laboratory of Green Materials for Light Industry, Hubei University of Technology, Wuhan 430068, China"},{"name":"Hubei Longzhong Laboratory, Xiangyang 441000, China"},{"name":"New Materials and Green Manufacturing Talent Introduction and Innovation Demonstration Base, Hubei University of Technology, Wuhan 430068, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2024,4,10]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1603167","DOI":"10.1002\/adma.201603167","article-title":"Recent progress on stretchable electronic devices with intrinsically stretchable components","volume":"29","author":"Trung","year":"2017","journal-title":"Adv. Mater."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1026","DOI":"10.1002\/pol.20220451","article-title":"Recent progress in fabrications and applications of functional hydrogel films","volume":"61","author":"Dong","year":"2023","journal-title":"J. Polym. Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1415","DOI":"10.1002\/adma.201203810","article-title":"Magnetochromatic microactuators for a micropixellated color-changing surface","volume":"25","author":"Kim","year":"2013","journal-title":"Adv. Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"140","DOI":"10.1039\/C4MH00147H","article-title":"Advances of flexible pressure sensors toward artificial intelligence and health care applications","volume":"2","author":"Zang","year":"2015","journal-title":"Mater. Horiz."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1353","DOI":"10.1021\/acsami.0c16719","article-title":"Multiple-stimuli-responsive and cellulose conductive ionic hydrogel for smart wearable devices and thermal actuators","volume":"13","author":"Chen","year":"2021","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"326","DOI":"10.1038\/nmat4489","article-title":"Hydrogels with tunable stress relaxation regulate stem cell fate and activity","volume":"15","author":"Chaudhuri","year":"2016","journal-title":"Nat. Mater."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"eaaf3627","DOI":"10.1126\/science.aaf3627","article-title":"Advances in Engineering Hydrogels","volume":"356","author":"Zhang","year":"2017","journal-title":"Science"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"e2201262","DOI":"10.1002\/adma.202201262","article-title":"Recent progress in smart polymeric gel-based information storage for anti-counterfeiting","volume":"34","author":"Sun","year":"2022","journal-title":"Adv. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"21890","DOI":"10.1002\/anie.202107281","article-title":"Aggregation-induced emissive carbon dots gels for octopus-inspired shape\/color synergistically adjustable actuators","volume":"60","author":"Wu","year":"2021","journal-title":"Angew. Chem. Int. Ed."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"108042","DOI":"10.1016\/j.dyepig.2019.108042","article-title":"Multi-responsive hydrogel actuator with photo-switchable color changing behaviors","volume":"174","author":"Zhang","year":"2020","journal-title":"Dyes Pigment."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"110364","DOI":"10.1016\/j.dyepig.2022.110364","article-title":"Multi-responsive chromatic hydrogel exhibiting reversible shape deformations","volume":"204","author":"Xiao","year":"2022","journal-title":"Dyes Pigment."},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Long, S., Huang, J., Xiong, J., Liu, C., Chen, F., Shen, J., Huang, Y., and Li, X. (2023). Designing Multistimuli-Responsive Anisotropic Bilayer Hydrogel Actuators by Integrating LCST Phase Transition and Photochromic Isomerization. Polymers, 15.","DOI":"10.3390\/polym15030786"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1604491","DOI":"10.1002\/adma.201604491","article-title":"Stimulus-responsive micro-supercapacitors with ultrahigh energy density and reversible electrochromic window","volume":"29","author":"Zhang","year":"2017","journal-title":"Adv. Mater."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"462","DOI":"10.1007\/s42114-019-00112-9","article-title":"Reversible photo-controlled release of bovine serum albumin by azobenzene-containing cellulose nanofibrils-based hydrogel","volume":"2","author":"Dai","year":"2019","journal-title":"Adv. Compos. Hybrid Mater."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1900404","DOI":"10.1002\/adom.201900404","article-title":"Designing molecular photoswitches for soft materials applications","volume":"7","author":"Boelke","year":"2019","journal-title":"Adv. Opt. Mater."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1706526","DOI":"10.1002\/adma.201706526","article-title":"Dynamic coordination of Eu-iminodiacetate to control fluorochromic response of polymer hydrogels to multistimuli","volume":"30","author":"Weng","year":"2018","journal-title":"Adv. Mater."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"8136","DOI":"10.1021\/acs.macromol.8b01496","article-title":"A tough and stiff hydrogel with tunable water content and mechanical properties based on the synergistic effect of hydrogen bonding and hydrophobic interaction","volume":"51","author":"Zhang","year":"2018","journal-title":"Macromolecules"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"1807328","DOI":"10.1002\/adma.201807328","article-title":"Reversible ion-conducting switch in a novel single-ion supramolecular hydrogel enabled by photoresponsive host-guest molecular recognition","volume":"31","author":"Wang","year":"2019","journal-title":"Adv. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1606900","DOI":"10.1002\/adma.201606900","article-title":"A novel design of multi-mechanoresponsive and mechanically strong hydrogels","volume":"29","author":"Chen","year":"2017","journal-title":"Adv. Mater."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"9320","DOI":"10.1039\/C5CC01064K","article-title":"Visible mechanochromic responses of spiropyrans in crystals via pressure-induced isomerization","volume":"51","author":"Meng","year":"2015","journal-title":"Chem. Commun."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1039\/C3CS60181A","article-title":"Spiropyran-based dynamic materials","volume":"45","author":"Klajn","year":"2014","journal-title":"Chem. Soc. Rev."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"51509","DOI":"10.1002\/app.51509","article-title":"Thermoresponsive nanocomposite hydrogels with high mechanical strength and toughness based on a dual crosslinking strategy","volume":"138","author":"Gu","year":"2021","journal-title":"J. Appl. Polym. Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"6213","DOI":"10.1038\/s41467-022-34044-8","article-title":"Force-triggered rapid microstructure growth on hydrogel surface for on-demand functions","volume":"13","author":"Mu","year":"2022","journal-title":"Nat. Commun."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"2108243","DOI":"10.1002\/adma.202108243","article-title":"Hysteresis-free nanoparticle-reinforced hydrogels","volume":"34","author":"Meng","year":"2022","journal-title":"Adv. Mater."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"2000127","DOI":"10.1002\/marc.202000127","article-title":"Programmed transformations of strong polyvinyl alcohol\/sodium alginate hydrogels via ionic crosslink lithography","volume":"41","author":"Li","year":"2020","journal-title":"Macromol. Rapid Commun."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"156","DOI":"10.1021\/acs.macromol.1c01115","article-title":"Modification of hydrophobic hydrogels into a strongly adhesive and tough hydrogel by electrostatic interaction","volume":"55","author":"Huang","year":"2022","journal-title":"Macromolecules"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"245","DOI":"10.1126\/science.abo4603","article-title":"Strong and fast hydrogel actuators","volume":"376","author":"Jiang","year":"2022","journal-title":"Science"},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Yang, Y., Shen, S., and Fan, D. (2021). A physicochemical double cross-linked multifunctional hydrogel for dynamic burn wound healing: Shape adaptability, injectable self-healing property and enhanced adhesion. Biomaterials, 276.","DOI":"10.1016\/j.biomaterials.2021.120838"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"3654","DOI":"10.1039\/C5TB00123D","article-title":"Fundamentals of double network hydrogels","volume":"3","author":"Chen","year":"2015","journal-title":"J. Mater. Chem. B"},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"193","DOI":"10.1016\/j.polymer.2018.08.029","article-title":"A highly tough and stiff supramolecular polymer double network hydrogel","volume":"153","author":"Li","year":"2018","journal-title":"Polymer"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"2005171","DOI":"10.1002\/adma.202005171","article-title":"Reversibly transforming a highly swollen polyelectrolyte hydrogel to an extremely tough one and its application as a tubular grasper","volume":"32","author":"Yu","year":"2020","journal-title":"Adv. Mater."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"9637","DOI":"10.1021\/acs.macromol.6b02150","article-title":"Metal-coordination complexes mediated physical hydrogels with high toughness, stick-slip tearing behavior, and good processability","volume":"49","author":"Zheng","year":"2016","journal-title":"Macromolecules"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"10418","DOI":"10.1021\/am403966x","article-title":"Strengthening alginate\/polyacrylamide hydrogels using various multivalent cations","volume":"5","author":"Yang","year":"2013","journal-title":"ACS Appl. Mater. Interfaces"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"972","DOI":"10.1039\/C3SM52666F","article-title":"A shape memory hydrogel induced by the interactions between metal ions and phosphate","volume":"10","author":"Yasin","year":"2014","journal-title":"Soft Matter"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"2456","DOI":"10.1021\/jp0689870","article-title":"Multiple steps and critical behaviors of the binding of calcium to alginate","volume":"111","author":"Fang","year":"2007","journal-title":"J. Phys. Chem. B"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/j.polymer.2017.05.070","article-title":"Hybrid dual crosslinked polyacrylic acid hydrogels with ultrahigh mechanical strength, toughness and self-healing properties via soaking salt solution","volume":"121","author":"Li","year":"2017","journal-title":"Polymer"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"e202300217","DOI":"10.1002\/tcr.202300217","article-title":"Switching it up: The promise of stimuli-responsive polymer systems in biomedical science","volume":"24","author":"Shymborska","year":"2024","journal-title":"Chem. Rec."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"362","DOI":"10.1021\/acsapm.3c02062","article-title":"Methoxy substitution enhances metal ion binding capacity of the water-soluble spiropyran copolymer","volume":"6","author":"Zeng","year":"2023","journal-title":"ACS Appl. Polym. Mater."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"111009","DOI":"10.1016\/j.dyepig.2022.111009","article-title":"Polyacrylamide\/sodium alginate photochromic hydrogels with enhanced toughness and fast response for optical display and rewritable information record","volume":"210","author":"Wu","year":"2023","journal-title":"Dyes Pigment."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"2000701","DOI":"10.1002\/marc.202000701","article-title":"High-performance photochromic hydrogels for rewritable information record","volume":"42","author":"Long","year":"2021","journal-title":"Macromol. Rapid Commun."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"3306","DOI":"10.1021\/ac1001004","article-title":"Spectroscopic analysis of metal ion binding in spiropyran containing copolymer thin films","volume":"82","author":"Fries","year":"2010","journal-title":"Anal. Chem."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"2094","DOI":"10.1039\/c3py01296d","article-title":"Tuning chelating groups and comonomers in spiropyran-containing copolymer thin films for color-specific metal ion binding","volume":"5","author":"Fries","year":"2014","journal-title":"Polym. Chem."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"8447","DOI":"10.1021\/jacs.0c02201","article-title":"Light-driven expansion of spiropyran hydrogels","volume":"142","author":"Li","year":"2020","journal-title":"J. Am. Chem. Soc."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1036","DOI":"10.1039\/C8PY01286E","article-title":"Trends in polymeric shape memory hydrogels and hydrogel actuators","volume":"10","author":"Shang","year":"2019","journal-title":"Polym. Chem."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/16\/8\/1031\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T14:25:26Z","timestamp":1760106326000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/16\/8\/1031"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2024,4,10]]},"references-count":44,"journal-issue":{"issue":"8","published-online":{"date-parts":[[2024,4]]}},"alternative-id":["polym16081031"],"URL":"https:\/\/doi.org\/10.3390\/polym16081031","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2024,4,10]]}}}